Photographic gelatin layer containing a polyglycerol monoester



Patented Apr. 2%, 194i PHOTOGRAPHIC GELATIN LAYER. CONTAIN- IN G A POLYGLYCEROL MONOESTER Nor-wood L. Simmons, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application March 2, 1940, Serial No. 321,902

7 Claims.

This invention relates to photographic lightsensitive materials, such as sensitized film, plates, and paper, comprising layers in which sensitive silver salts are suspended or dispersed in gelatin or other suitable vehicle, and optionally comprising other layers as well. More particularly, it relates to the use of certain agents to facilitate the spreading of gelatino-silver-halide layers and, in fact, the spreading of any gelatin or other hydrophilic colloid layers which are deposited from a predominantly aqueous medium and used in such photographic materials.

My invention perhaps finds its greatest usefulness in the manufacture of photographic film in which a sensitive gelatin emulsion layer is applied to the film base, set by chilling, and them, without drying, is overcoated with a protective gelatin layer, the sensitive gelatin emulsion layer containing such a spreading agent. The general process of coating film base with a sensitive gelatin emulsion layer, setting by chilling, and overcoating with a protective gelatin layer, is fully set forth in U. S. Patent No. 1,699,349 of William B. Dailey.

If a sensitive gelatino-silver-halide emulsion is coated on a film base (which has usually first to the sensitive emulsion in order to avoid these defects as far as possible. Saponin has surfaceactive properties, and not only acts as a spreading agent for gelatin, but by some mechanism not clearly understood, it prevents the formation of air bubbles between the gelatin layers when a wet, chilled gelatin emulsion layer containing the proper concentration of saponin is overcoated with a warm gelatin solution.

However, saponin, being a naturally occurring material of vegetable origin, is of varying quality, and synthetic agents are to be preferred because of their more constant and controlled properties. Because of its varying quality, some batches of saponin may cause an increase in fog or a decrease in sensitivity in the sensitive emulsion, and in some cases may produce little or no improvement in spreading. This is true whether the saponin be employed in the-emulsion layer or in the protective overcoating or other layer.

Other surface-active materials have been tried in place of saponin, but many of them, while they may act to some'extent as spreading agents for gelatin, have been found to be entirely inefiective for preventing the formation of air bubbles when a wet, chilled gelatin emulsion containing them is overcoated with a warm gelatin solution, and many of them are objectionable from the stand point of fogging or desensitizing the emulsion.

.in layers such as sensitive gelatin emulsions, are

superior to saponin in the prevention of bubble formation when the wet, chilled emulsion layer is overcoated with a warm gelatin solution or other hydrophilic colloid of the type which is deposited from a predominantlyaqueous medium. These compounds are the water-soluble monoesters of polyglycerols containing at least 4 glycerol radi-' cals with an acid selected from the group consisting of the aliphatic acids of from 8 to 18 carbon atoms and the alicyclic acids. They may be prepared by partial esterification of polyglycerols containing at least 4 glycerol radicals, e. g., tetraglycerol, with the acids defined, for example, lauric, myristic, pelargonic, lauroxyacetic, oleic, ricinoleic, naphthenic, abietic, hydroabietic, ,3- thiolaurylacetic or dihydroxystearic acid, for instance-in the ways described in U. S. Patent 2,022,766 of Benjamin R. Harris, U. S. Patent 2,071,459 of Reginald Furness, and U. S. Reissue Patent 21,322 of Benjamin R. Harris. Of the aliphatic acids, lauric is preferred; The polyglycerol monoesters of aliphatic acids containing above 14 carbon atoms tend to be insufiiciently water-soluble for the purpose of my invention. The presence of a double bond, as in oleic acid, aids water-solubility.

These polyglycerol monoesters may be incorporated in the sensitive gelatin emulsion at any point in its manufacture such that they will be present during its coating, in the proportion of from 0.002 to 0.2 part of ester per parts by weight of wet emulsion. This gives a polyglycerol monoester content of 0.02% to 2% in the dried emulsion layer. They have no detrimental effect upon the photographic properties of the emulsion, but, on the contrary, improve them. For

example, they improve the aging qualities of the emulsion. Photographic films in which the sensitive emulsion contain the above-mentioned proportions of the polyglycerol mono-esters defined have been found to show higher speed and less fog after prolonged storage at elevated temperatures than ordinary film, stored for the same length of timeunder the same conditions. They are also more readily wet by the developing solution.

It is believed that the property of the spreading agent which prevents the formation of air lbubbles when a wet, chilled gelatin emulsion is overcoated with a warm gelatin solution, also tends to prevent the formation of air bubbles, repellent spots, etc., on the surface of a sensitive emulsion containing such a spreading agent, when that emulsion, coated on a film, plate, paper, etc., is immersed in a developer.

As above pointed out, the polyglycerol monoesters defined may be used in any one or more of the colloid layers used to build up a photographic sensitive element upon a base such as film, glass, paper, etc., which layers consist of gelatin. or other hydrophilic colloid which is deposited from a predominantly aqueous medium, i. e., a medium used as the solvent for such materials in which water predominates, the remainder of the medium contributing to give a good dispersion of the colloid. Ii two superposed colloid layers are present, either, neither. or both of which may be photographically sensitive, agent may be used in either layer or in both layers. However, where a wet, chilled lightsensitive gelatin or similar layer is to be overcoated with a warm solution or emulsion of gelatin or similar material, the presence of the spreading agent inthe wet, chilled layer is essential for preventing the formation of air bubbles between the layers. Examples of such hydrophilic colloids other than gelatin, which are usefulas. layers in photographic films, plates, paper, etc., are the water-soluble cellulose derivatives such as well hydrolyzed cellulose acetate (described in U. S. Patent No. 2,110,491 of $21.10) and cellulose esters of hydroxy monocanboxylic acids, such as lactic or glycollic, and salts of cellulose esters of dicarboxylic acids, such as phthalic (described in U.S. Patent No. 2,127,573 of Sheppard and U. S. Patent No. 2,127,621 of Staud), as well as polyvinyl alcohol and hydrolyzed polyvinyl acetate (described in applications the spreading of Wesley G. Lowe, Serial Nos. 318,559 and r 318,560, filed February 12, 194.0) and water-soluble polyvinyl acetals (described in an application of Charles R. Fordyce, Serial No. 221,584, filed July 27, 1938, Patent No. 2,211,323). When colloids other than gelatin are used, it may be desirable to coat them at different temperatures.

In the claims appended hereto, where a hydrophilic colloid depositable from a predominantly aqueous medium is referred to, it will be understood to mean any hydrophilic colloid which can be deposited from a medium which is predominantly aqueous, the remainder of the medium being an organic solvent which contributes to the dispersibility of the colloid;

examples of such organic solvents for this purpose are acetone, ethyl alcohol, ethylene glycol, monoacetin and pyridine.

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

1. Photographic sensitive material comprising a layer of a hydrophilic colloid depositable from a predominantly aqueous medium, said layer containing from 0.02% to 2% of a water-soluble monoester of a polyglycerol containing at least 4 glycerol radicals with an acid selected from the group consisting of the aliphatic acids of from 8 to 18 carbon atoms and the alicyclic acids.

2. Photographic sensitive material comprising a gelatin layer containing from 0.02% to 2% of a water-soluble monoester of a polyglycerol containing at least 4 glycerol radicals with an acid selected from the group consisting of the aliphatic acids of from 8 to 18 carbon atoms and the alicyclic acids.

3. Photographic sensitive material comprising a base and two superposed gelatin layers, in which the gelatin layer nearer the base contains from 0.02% to 2% of a water-soluble monoester of a polyglycerol containing at least 4 glycerol radicals with an acid selected from the group consisting of the aliphatic acids of from 8 to 18 carbon atoms and the alicyclic acids.

' 4. Photographic sensitive material comprising a base, a photo-sensitive gelatin emulsion layer and a gelatin. overcoating on the emulsion, in which the photo-sensitive gelatin emulsion layer contains from 0.02% to 2% of a water-soluble monoester of a polyglycerol containing at least 4 glycerol radicals with an acid selected from the group consisting of the aliphatic acids of from 8 to 18 carbon atoms and the alicyclic acids.

5. Photographic sensitive material comprising a gelatin layer containing from 0.02% to- 2% of a monolaurate of a polyglycerol containing at least 4 glycerol radicals.

6. Photographic sensitive material comprising a gelatin layer containing from 0.02% to 2% of a mononaphthenate of a polyglycerol containing at least 4 glycerol radicals.

7. Photographic sensitive material comprising a gelatin layer containing from 0.02% to 2% of a mono-hydroabietate of a polyglycerol containing at least 4 glycerol radicals.

NORWOOD L. SIMMONS. 

